Germany, since 1949 a well-run and very successful country, should obviously have a seat on the UN Security Council. The idea has been mooted for some time. But it was her own best-known foreign minister, Hans-Dietrich Genscher, who refused to pursue the idea. It would be, he said, like giving a liqueur chocolate to an alcoholic. He knew whereof he spoke.

As an 18-year old, he had been a soldier in the absurd and literally last-ditch attempts to hold off the Russian assault on Berlin in 1945, the whole atmosphere of which is so splendidly captured by the film Der Untergang, in which Hitler, in his bunker, defied the world until the Russians had taken the Prussian finance ministry down the road, whereat Hitler made the most infamous shotgun marriage in history, dictated a political testament to the effect that it was all the Jews' fault, had a vegetarian wedding breakfast, and then shot himself, the happy bride's wedding toast being cyanide. The final faithful knew that the Hitler Reich had come to an end when cigarette smoke came up the ventilation shafts. Hitler had been a fanatical anti-smoker, and, Hitler gone, the secretaries lit up. The film has a very good ending, in which one of them finds a bike and pedals off with a small boy towards the west: hope. Genscher himself lived for a time in the Russian-occupied east but then himself went west, to prosper and, eventually, to preside over the end of the Berlin Wall. But his early experiences of his own country, its beyond-surreal combination of efficiency and craziness, made him not really want to have a foreign policy at all. His memoirs are unreadable.

The background to this is the subject of Mark Mazower's book. In 1940-41, by fluke circumstance imposed upon fluke circumstance, Hitler found himself ruler of an empire larger than Napoleon's. There were Germans in the Channel Islands, there were Germans on the territory of today's Moscow airport, there were Germans admiring the ruins in Athens, there were above all Germans in Paris. Western Europe had collapsed (the general invading Denmark had screamed "get this country out of the way, we are invading somewhere else"), and wars with Poland and then Russia had led to another tremendous collapse. By the end of 1941, the German army had taken prisoner more than two million Russians, and there was a Generalgouvernement in Poland, run from Krakow, where the governor-general, Hans Frank, fancied himself as a Renaissance prince and was foolish enough to assemble 40 books of diaries, eventually quite enough to hang him.

Then the Germans were stopped. The next few months still went badly for the Allies, and it took them three further years before Hitler was finally ground down, the British in Hamburg, the Russians in Berlin. There was, therefore, a German occupation of Europe, whether direct or - through satellites such as Croatia or Slovakia - indirect.

What did the Germans do with this? Something similar had happened with Napoleon. But in his case, the domination, though bullying and crude, was not entirely negative, because it did get rid of feudalism and it did cut back the dead weight of clericalism (in Naples, before his time, one-twentieth of the population consisted of monks and nuns). Hitler's occupation, in contrast, was unrelentingly negative. The unrelentingness of the negativity is displayed on page after page of Mazower's splendid book. He has constructed it very well, and avoided the wooden method of going through individual countries - Slovakia one page, Croatia another, the Crimea another, etc - which only makes for repetition. He manages cleverly to combine theme and chronology, and so can concentrate information when he wants to (he is very good on the cultural collaboration of men such as Cocteau with Hitler's favourite sculptor, Arno Breker, for instance). It is a relentlessly gruesome story, filled with gruesome characters who, even at the very end, behaved with ridiculous self-importance and with not a trace of remorse. There is a photograph of the Nazi elite, mustered at a castle in Luxembourg for interrogation. They look like school prefects.

There were of course the grandiose schemes for the remaking of the whole continent - Jews eliminated, Ukrainians shoved into trains for compulsory labour, Poles to be dumped in featureless plains so that masses of Germans could take their houses and farms. On the other side was an extraordinary pettiness, as with the elderly Jewesses surviving in Berlin who were refused permission to buy seed for their budgerigars, or the tobacco sellers in Warsaw who were forbidden to sell single cigarettes.

What is so extraordinary about this story is the self-destructiveness involved. There probably was an opening for a Europe run (as is today's) in large part from Berlin. In occupied France, Belgium or Holland, there were great numbers of people who eagerly went along with the idea. It got nowhere. Some Germans did indeed argue for cross-border collaboration, but others were all for forcing French and Dutch labourers to work as slaves in Germany proper, and it was they, whipping young boys on to packed trains, who won. The French aircraft industry, the greatest in Europe, produced all of six aircraft in 1943. Resistance grew, and played an important part in liberation. In eastern Europe, the German failure was still greater.

Nowadays, we have Ukraines and Lithuanias that cooperate well with Germany; the case of the Czech Republic is even more striking, given the past. But in Hitler's time, German behaviour on the ground was such that they all, in the end, went along with Stalin.

Germany faced a terrible retribution, in the form of the British bombing of its cities. This, starting with a firestorm in Hamburg in the summer of 1943, turned many of these cities into moonscapes, and even at the very end the RAF was still destroying harmless places such as Rothenburg ob der Tauber or even Bayreuth. Some 20 years ago, the Queen Mother attended a ceremony at the top of the Strand, where a statue was put up to Air Marshal "Bomber" Harris, who had been the strategist of it all. I remember protesting and being firmly told by a friend, the late Lionel Bloch, who had grown up in German-dominated Bucharest, that the Germans would never have learned to behave properly if it had not been for that hail of bombs. He had seen them in their prime. So had Genscher.

· Norman Stone's World War One: A Short History is published by Penguin